Fuel cells may convert chemically bound energy directly into electrical energy. Fuel cells presently may consume hydrogen and oxygen and may convert these elements into the environmentally safe end product water.
It is believed that methods of partial oxidation, autothermal reforming as well as steam reforming have been used in fuel cell applications to produce a hydrogen-rich gaseous stream of hydrocarbons. Gas purification stages may be provided to reduce the carbon monoxide content in the gaseous stream to approximately 100 ppm, for example, for a low-temperature fuel cell. Several process steps may be provided for this purpose that may result in considerable process and configuration expense. In addition, this may cause relatively high costs for process development, production, and a comparatively high need for maintenance of the total system.
The method of catalytic decomposition has been used for the production of black carbon. In catalytic decomposition, hydrocarbons, methane or the like in particular, may be primarily converted into hydrogen and carbon in the form of black carbon. This reaction may proceed at low pressures and may occur with heterogeneous catalysis in order to accelerate the endothermic decomposition reaction according to equation 1:
 CH4<=>C(s)+2H2ΔH(1000K)=+89.8kJ/mol(CH4)  (1)
If no continuous removal of black carbon is ensured, the carbon being deposited in the reactor according to equation 1 may be required to be removed periodically in order to reduce or remove the black carbon deposit on the catalyst. Thus, the hydrogen-rich gas mixture may be produced in a first operating phase and the black carbon may be removed in a second operating phase in order to prevent the reactor from becoming clogged.
Black carbon may be removed, for example, by oxidation reactions according to equations 2 and 3:C(s)+0.5O2=>COΔH(1000K)=−112.0 kJ/mol(CO)  (2)CO+0.5O2=>CO2ΔH(1000K)=−282.9 kJ/mol(CO2)  (3)
As an alternative, black carbon may be oxidized through a fluid stream containing steam:C(s)+H2O=>H2+CO2+CH4ΔH(298K)=−132kJ/mol  (4)
As research reports may show, efficient carbon decomposition may be attained. Industrially, this reaction may be used for carbon burn-off in steam reforming processes; if an oxygen-containing gas is added, the burn-off may proceed even more easily according to equations (2) and (3).
Heretofore, catalytic decomposition for fuel cell applications may have only been implemented in the laboratory (see Poirier, M. G. (1997): “Catalytic decomposition of natural gas to hydrogen for fuel cell applications,” Int. J. Hydrogen Energy 22 (4), 429-433). In this connection, the periodic oxidation of the black carbon deposits was investigated with changeover between two separate reactors.